Cellulose-acetate composition of low inflammability



l sitivve photographic coatings.

- which it is associated durin storage or use. urther ob ects will here- Patent ed .lune 7, l f p UNITED STATES- Ro Drawing;

I This invention relates to; cellulose acetate lo films that are substantially waterproof, are

unaifected by ordinary photographic baths,

combine low inflammabilitywith practical freedom from color and possess, in short,

the desired properties of a-support for sen- Still 7 another objectofmy invention is to produce a composition which. may be used in film, varnish or plastic manufacturing without injuryto or being' injured .by the substances with manufacture,

inafter'ap ear.

1 I have ound that cellulose'acetate compositions having the desirable qualities enumerated above can be obtained by mixing j I invention I may dissolve 100-parts of cellucellulose acetate, preferably of the acetone- I p 1 b1 type, with a brom-nucleo-substitution productof the phenols and their liomologues,

said mixture'bein'g efiectively neutral and 3 said substitution roduct being substantially -free from uncom ined bromine and hydro- I bromic acid. By efl'ectively neutral Imean 'that 'there is-not'present in the a 4 high enou h concentration of acid to break' down or li rate bromine from the substitution product -I may employ any zone ormore of the brominated monohydric and. polyhyd'r'ic. phenols.- and their homologies-,1 such ascarbolic acid, catechol, resorcinol,. 40 hydrochinone, pyrogallol, phloroglncinol,

cresol, thymol, etc.', provided that the one or more bromine atoms are joined directly to'a carbon in the ring. I prefer, at present,

to use tribron o henol, 'para'bromo handand bromohydroc inone, but itwill' ders'too'd' that-my invention is not restricted to these individual substances, except as indicated in .the appended claims.

- Compositions of cellulose acetate and such 7 brom substitution productsha've a surprising degree of practical.. noninflammai )1lity,-- that is, an unexpected slowing down of the propagation of combustion therein. Films of such compositions, when. ignited,- often is go out and must be reignited several -I can combine 100 1. 51. 68 PATIENT oF lcE.

\ srawam: .1. cannon, or nocnnsraa, nnw YORK, a'ssrenon 'r'o nasrmn xonnx comrm, or ROCHESTER, NEW YORK, A conroaa'rron on NEW Yoax.

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Application-filed spinal,- 1925. Serial 30,26,309.

during the test, the flame traveling along the I I film very slowly.

Unless certain precautions are taken, films embodying such compositions may become discolored beyond the manufacturing tolerance which is permissible. The first precaution is to free the brom substitution product from free bromine and free hydrobromic acid. .The'other precaution is to keep the mixture effective neutral so that vthere will be insufiicient acid to'splitup the substitution products. -I consider films resulting from theseprecautions to be colorless when they fall within the customary manufacturing tolerances as regards color.

' In one form ofmy invention I ma solve 100 parts by weight of acetonesoluble cellulose acetate in 300 to 500 parts of acetone, along with'5 to'75 parts of tribromo-' phenol. Such a composition, say one containing 400 parts of acetone and 30 parts of tribromophenol to 100 parts of cellulose acetate, is suitable for manufacturing by 7 the usual methbdsfi I In another illustrative embodiment of my .bromophenol; This-is likewise-suitable for film manufacture. a

' In still a difierent form of my invention parts of cellulose acetate with 5 to ..(Say"30) parts offbromohydro chinoneby dissolving them in 300 to 500 (say 400) parts of: acetone.

'lhe ingredients are; mixed thoroughly-to fo'rm a homogeneous soloution v or flowable mass which. is' filtered, if desired. When more flowable solutions are desired,'or when the compositionslare to be egiployed as lacquers, the volatile;, solvent m 4 I y'be increased,- as will be understood by thoseskilled iii the art, orvolatile non-solvents, such as benzol, alcohol, and thelike may beadded,

but not to the point where precipitation occurs. Along with theingredientsgiven in the-above examples, I ma add one or more organic bodies'of only slight volatility which enhancethe plasticity or flexibility of the compositions, and regulate Qthepreparaftion of film therefrom; but such bodies are. not preferred or essential. Examples of them are amyl or butyl acetate, the various amdyl alcohols, the fvai'iou'sbuty'l alcohols, an

mixtures ofthem. y

Films prepared from the hereinabove described compositions are flexible, smooth, transparent and suitable for photographic purposes. Moreover, the absence of free bromine and free hydrobromic acid, initially and throughout the useful life of the film s, prevents, injury to any photographic coatings or discoloration of the composition.

.Of course, asmall amount of a substance (like dic'yan'diamine) which absorbs bromine and, blends with the other ingredients of the film without injuring the photographic coatings my be incorporated in the compositions as an insurance against trouble, but this is unnecessary when the composition is prepared with reasonable care while forth.

observing the precautions hereinafter set Having thus described 1. An eifective neutral composition of matter comprising cellulose acetate, and at least one of the brom-nucleo-substitution products of the phenols and their homologues which is substantially free from uncombined bromine and hydrobromic acid.

2. An effectivelyneutral composition com- I prising celluloseacetate, at least one of the and by brom-nucleo-substitution products of" the phenols and their homologues which'is substantialliy free from uncombined bromine mon-to said in' edi'ent's. 3. A flowab e film-forming composition comprising cellulose acetate, at least one of the brom-nucleo-substitution products of the phenols and their homologues which is substantiall free from uncombined bromine and h d only 'ght volatility that enhances the flexibility' of the films, and a volatile solvent common all said ingredients.

my invention, what -I claim as new and desire to secure by Letters Patent is:

robromic acid and a solvent com-- robroniio acid, an organic body. of

fcomprising acetone-soluble cellulose acetate,

tribromophenol substantially free from'uncombined bromine and hydrobromic acid and a solvent common to said ingredients.

7 As an article of manufacture a flexible, transparent, substantially colorless fihn comprising cellulose acetate and at least one of the brom-nucleo-substitution products of the phenols and their homologues substantially free from uncombined bromine and hydrobromic acid.

8. A flexible, transparent, substantiallyv colorless film. which is substantiallyv inert toward photographic coatings, which comprises acetone-soluble cellulose acetate, and

at least 'oneof the brom-nucleo-substitution products of monohydric phenols and their .homologues which is substantially free from uncombined bromine and hydrobromic acid."

9. As an article of manufacture; a substantially colorless flowed film, which is substantially inert toward photographic coatings which com rises acetone-soluble cellulose acetate an tribro'mophenol which is substantially free from uncombined bromine and hydrobromic acid.

Signed at Rochester, New York, this 25th day of April, 1925.

. STEWART J. CARROLL. 

